The aircraft struck a tree and subsequently the ground while descending well below the correct final approach path in controlled flight. The ambient conditions and landing environment were such that both the instructor and student were likely affected by the black-hole illusion. The black-hole illusion would influence the pilots' perceptions of the aircraft altitude, and allow the pilots to unknowingly descend below a safe altitude if they did not make appropriate reference to the aircraft altimeter. In addition, the runway was only 100 feet wide, whereas the student had practised his previous night approaches and landings on a runway 200 feet wide, and the runway had no approach lights or final approach glide path indicator systems.Analysis The aircraft struck a tree and subsequently the ground while descending well below the correct final approach path in controlled flight. The ambient conditions and landing environment were such that both the instructor and student were likely affected by the black-hole illusion. The black-hole illusion would influence the pilots' perceptions of the aircraft altitude, and allow the pilots to unknowingly descend below a safe altitude if they did not make appropriate reference to the aircraft altimeter. In addition, the runway was only 100 feet wide, whereas the student had practised his previous night approaches and landings on a runway 200 feet wide, and the runway had no approach lights or final approach glide path indicator systems. The instructor and student were properly qualified and fit for the training flight. Records indicate that the aircraft was certified and maintained in accordance with existing regulations, and there was no evidence found of any aircraft malfunctions that could have contributed to the accident. The aircraft struck a tree at low level and crashed during a visual final approach at night to runway 10. The ambient conditions and landing environment were conducive to black-hole illusion on final approach. The final approach was flown without reference to the aircraft altimeter.Findings The instructor and student were properly qualified and fit for the training flight. Records indicate that the aircraft was certified and maintained in accordance with existing regulations, and there was no evidence found of any aircraft malfunctions that could have contributed to the accident. The aircraft struck a tree at low level and crashed during a visual final approach at night to runway 10. The ambient conditions and landing environment were conducive to black-hole illusion on final approach. The final approach was flown without reference to the aircraft altimeter. Neither the instructor nor the student monitored the aircraft's altitude during the night visual approach, and the ambient conditions and landing environment were conducive to black-hole illusion.Causes and Contributing Factors Neither the instructor nor the student monitored the aircraft's altitude during the night visual approach, and the ambient conditions and landing environment were conducive to black-hole illusion.